This invention is in the field of digital computers. Specifically, it is a method and apparatus for placing the computer in an `idle` or `sleep` power saving mode while the computer waits for input.
In any computer, the speed of the computer's internal clock determines the rate of data processing. If all other factors are constant, a faster clock rate will result in faster processing. The penalty for faster processing is, unfortunately, increased power consumption. Every clock pulse causes at least some of the transistors in the central processing unit (`CPU`) to change state. This change of state consumes power. Thus, the faster the clock rate, the more often transistors change state and the more power is consumed.
Although increased power consumption is not a major problem when a conventional A.C. power supply is available, it is a problem when batteries are used as the power source. To increase the useful operating time of computers powered by batteries, any means for reducing power consumption without impairing the operation of the computer is desirable.
One particular area where power savings may be realized is during the times when the computer is waiting for input from a keyboard or from an interface port. During these periods, the CPU continues to function in its standard mode, despite there being no work to do. Consequently, despite the fact that nothing is accomplished, power requirements are unchanged. A device or method which would reduce the power consumption of the CPU during these periods of waiting for data input is clearly desirable.